sidechain stopped importing parentchain blocks but continued producing sidechain blocks

[brenzi]

2025-01-17 12:00:02.215	
[2025-01-17T11:00:02.215Z WARN  substrate_api_client::rpc::tungstenite_client::client] Connection attempt failed due to Io(Custom { kind: Uncategorized, error: "failed to lookup address information: Name or service not known" })
...
2025-01-17 12:00:32.279	
[2025-01-17T11:00:32.278Z ERROR integritee_service::ocall_bridge::ffi::worker_request] Worker request failed: NodeApiFactory(FailedToCreateNodeApi(RpcClient(MaxConnectionAttemptsExceeded)))
2025-01-17 12:00:32.279	
[2025-01-17T11:00:32.278Z ERROR integritee_service::sidechain_setup] Sgx(SGX_ERROR_UNEXPECTED)
2025-01-17 12:00:41.875	
[2025-01-17T11:00:41.874Z ERROR integritee_service::main_impl] [TargetB] parentchain block syncing terminated with a failure: ApiClient(RpcClient(MaxConnectionAttemptsExceeded))

remedy:

• restart the validateer
• verified that shielding events during stall will be caught up upon restart (no loss of funds due to this issue) logs
• added AlertManager rule to watch parentchain block imports

observations:

• it seems that prometheus wasn't reachable from the outside prior to this event. metrics are missing